fix bug when use extern_openblas and generator is ninja (#39428)

* fix bug when use extern_openblas and generator is ninja

* modify according to zhouwei's comment

cmake/external/openblas.cmake

@@ -55,6 +55,7 @@ IF(NOT WIN32)
         INSTALL_COMMAND     make install NO_SHARED=1 NO_LAPACK=1 PREFIX=<INSTALL_DIR> 
         UPDATE_COMMAND      ""
         CONFIGURE_COMMAND   ""
+        BUILD_BYPRODUCTS    ${CBLAS_LIBRARIES}
     )
 ELSE(NOT WIN32)
     SET(CBLAS_LIBRARIES
@@ -83,6 +84,8 @@ ELSE(NOT WIN32)
         CMAKE_CACHE_ARGS    -DCMAKE_INSTALL_PREFIX:PATH=${CBLAS_INSTALL_DIR}
                             -DCMAKE_POSITION_INDEPENDENT_CODE:BOOL=ON
                             -DCMAKE_BUILD_TYPE:STRING=${THIRD_PARTY_BUILD_TYPE}
+        # ninja need to know where openblas.lib comes from
+        BUILD_BYPRODUCTS    ${CBLAS_LIBRARIES}
         )
     SET(OPENBLAS_SHARED_LIB  ${CBLAS_INSTALL_DIR}/bin/openblas${CMAKE_SHARED_LIBRARY_SUFFIX})
 ENDIF(NOT WIN32)